A PowerPoint Template is a file that can contain commonly used settings to make producing future PowerPoint Presentations and Shows easier. POTX PowerPoint Templates are different than the POT version in that they use the Microsoft Office Open XML format.
Since 2007, Microsoft began to use a file format docx, which is created by using the Office Open XML. The format is a zip-file containing the text in the form of XML, graphics and other data that can be translated into a sequence of bits using patent-protected binary formats. At first it was assumed that this format will replace the doc, but both formats are still used today.